Joining the navy in 1968, Scarce served during the Vietnam War on the troop transport HMAS Sydney.[2] After the Vietnam War, Scarce's naval career specialised in military logistics and procurement, rising to the rank of rear admiral and head of Maritime Systems at the Defence Materiel Organisation. Scarce also served as the commander of HMAS Cerberus between 1995 and 1997.

On 3 May 2007, it was announced that Scarce would become Governor of South Australia – the Queen's representative in the state, although after his appointment he broke the tenets of viceregal impartiality by publicly stating that he is an avowed supporter of an Australian republic.[4] When appointed, he was the youngest South Australian-born Governor and the first Royal Australian Navy officer appointed to the position.[5] In 2008, during his term as Governor, Scarce was appointed the Patron of Debating SA. On 13 February 2012, Scarce's term was extended by two years to 7 August 2014.[6]Hieu Van Le, Scarce's lieutenant-governor, was announced on 26 June 2014 as Scarce's replacement, and took over the role on 1 September.[7]

Scarce was appointed Chairman of the Cancer Council of South Australia in November 2014[8] and has since met many beneficiaries of the organisation's fundraising, research, education and services. He told The Advertiser that he took the role last November after being impressed by the Council's work during his time as Governor, and also because his grandmother Leah died from cancer. Scarce has also cycled as part of the Cancer Council's Ride for a Reason team in the SantosTour Down Under.[9]

Scare was appointed the 16th Chancellor of the University of Adelaide with effect from 1 December 2014[10] in succession to the Hon Robert Hill AC, who retired in July 2014. In the interim, Deputy Chancellor, Dianne Davidson, was the Acting Chancellor of the University.

In December 2014, Scarce broke seven years of 'political silence' by suggesting that South Australia considers developing nuclear industries to compensate for a downturn in the manufacturing sector. He said that a debate between experts and without political intervention was needed. He was speaking as an invited guest of the South Australian Chamber of Mines and Energy (SACOME).[11]

Earlier that month, Scarce had been appointed Chancellor of the University of Adelaide. Several of the University's staff had previously announced their support for the development of nuclear power generation as a means of reducing carbon emissions and mitigating climate change. Examples include Professor Barry Brook,[12] scientists Tom Wigley[13] and Corey J. A. Bradshaw[14] and economist Mike Young.

Scarce appeared in a segment about the nuclear Royal Commission on ABC's 7.30 program, broadcast on 14 March 2015. He said:

“I know the dangers of the industry. I also know the opportunities it can bring. How do we convince South Australians that it is safe... and what are the benefits of so doing?”[16]

A period for public submissions in response to the Terms of Reference for the Commission closed that afternoon, prior to the 7.30 broadcast.[17]

During his role as Governor of South Australia, Scarce spoke and presented the deed of title at the Maralinga Tjarutja Section 400 Handback Ceremony at the Maralinga Village.[18] Section 400 was a 3,126 km2 parcel of land, located 136 kilometres (85 mi) from the Oak Valley Aboriginal Community. The ceremony marked the return of Section 400 to its traditional owners, which had previously been disallowed access due to radioactive contamination. The contamination was a legacy of a program of British nuclear weapons tests which ran from 1956 until 1963. Seven major nuclear weapons tests occurred in 1956 and 1957 followed by a series of 'minor' tests which included the explosive scattering of 22 kilograms (49 lb) of plutonium.[19]

Scarce spent his early childhood in Woomera, home of the Commonwealth Weapons Research Establishment. The WRE, as it was known, served as a support centre for the British nuclear test program during this period.

11 June 2001: Member of the Order of Australia (Military division) for exceptional service to the Royal Australian Navy as Commander Training Command – Navy, and as Support Commander – Navy.[21]

26 January 2004: Officer of the Order of Australia (Military division) for distinguished service in logistics management and acquisition as the Head, Maritime Systems Division in the Defence Materiel Organisation.[22]

26 January 2008: Companion of the Order of Australia (General division) for contributions to Australia's defence industry through the provision of leadership and strategic advice on the development of naval capabilities, to maritime transport management, and to the people of South Australia.[23]

In 1975, Scarce married Elizabeth Anne Taylor while posted at HMAS Watson. They have two adult children, Kasha (born in 1978), who works as a social worker in Sydney; and Kingsley (born in 1980), who serves as a lieutenant commander in the Royal Australian Navy.